[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 101720
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU SEP 10 2015

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE
EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE
IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1645 UTC.

...SPECIAL FEATURES...
TROPICAL STORM HENRI IS CENTERED NEAR 32.6N 60.8W AT 10/1500 UTC
OR ABOUT 205 NM E OF BERMUDA MOVING N AT 8 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 1008 MB. MAXIMUM SUSTAINED WIND SPEED IS 35
KT WITH GUSTS TO 40 KT. SCATTERED MODERATE CONVECTION IS FROM
29N TO 35N BETWEEN 54W AND 61W. SEE LATEST NHC FORECAST/ADVISORY
UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...
A TROPICAL WAVE IS EMERGING OFF THE COAST OF W AFRICA TODAY WITH
AN AXIS THAT EXTENDS FROM 18N15W TO 09N15W. A MODERATE SURGE OF
MOISTURE IS INDICATED IN SSMI TPW SEVERAL HUNDRED MILES AHEAD OF
THE WAVE. SCATTERED MODERATE CONVECTION IS FROM 05N TO 18N
BETWEEN THE AFRICAN COAST AND 22W.

A TROPICAL WAVE OVER THE CENTRAL ATLC HAS AN AXIS THAT EXTENDS
FROM 19N31W TO 10N34W MOVING W AT 15 KT. THE WAVE COINCIDES WITH
A RELATIVELY SHARP 700 MB TROUGH AND A MAXIMUM IN 850 MB
RELATIVE VORTICITY. THE WAVE IS EMBEDDED IN A BROAD AREA OF
MODERATE MOISTURE. SCATTERED MODERATE CONVECTION IS FROM 07N TO
14N BETWEEN 30W AND 40W.

A TROPICAL WAVE...THE REMNANTS OF GRACE...EXTENDS OVER THE
CENTRAL ATLC FROM 19N56W THROUGH A 1011 MB LOW NEAR 15N56W...TO
11N57W...MOVING W AT 20 KT. SSMI TPW INDICATES A POLEWARD SURGE
IN MOISTURE ALONG THE WAVE AXIS. SCATTERED MODERATE CONVECTION
IS FROM 11N TO 17N BETWEEN 53W AND 63W.

A TROPICAL WAVE OVER THE EASTERN CARIBBEAN HAS AN AXIS THAT
EXTENDS FROM 18N68W TO 10N69W MOVING W AT 20 KT. SSMI TPW SHOWS
THIS WAVE IS AT THE LEADING EDGE OF A LOW AMPLITUDE SURGE OF
MOISTURE. NO DEEP CONVECTION IS CURRENTLY OCCURRING WITH THIS
WAVE.

A TROPICAL WAVE OVER THE WESTERN CARIBBEAN HAS AN AXIS THAT
EXTENDS FROM 17N82W TO 09N83W...MOVING W AT 20 TO 25 KT. DEEP
MOISTURE IS NOTED S OF 14N WITH THE EASTERN EXTENSION OF THE
EASTERN PAC MONSOON TROUGH ALONG THE SOUTHERN EDGE OF THE WAVE.
SCATTERED MODERATE/STRONG CONVECTION IS S OF 14N W OF 78W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 13N17W TO
10N33W WHERE THE ITCZ BEGINS AND CONTINUES TO 09N45W TO 13N54W.
OTHER THAN CONVECTION ASSOCIATED WITH THE TROPICAL WAVE EMERGING
OFF THE COAST OF AFRICA AND THE TROPICAL WAVE OVER THE EASTERN
ATLC NEAR 31W/33W...ISOLATED MODERATE CONVECTION IS WITHIN 125
NM OF THE MONSOON TROUGH AND ITCZ AXIS.

...DISCUSSION...

GULF OF MEXICO...
A MID TO UPPER LEVEL TROUGH EXTENDS FROM THE OHIO VALLEY TO THE
N CENTRAL GULF. SHORTWAVE ENERGY MOVING ACROSS THE NW GULF
TOWARD THE BASE OF THE TROUGH IS SUPPORTING SCATTERED
THUNDERSTORMS FROM 27N TO 30N BETWEEN 90W AND 98W. DOWNSTREAM OF
THE TROUGH...ASCENT IS INTERACTING WITH A MODERATELY MOIST
ATMOSPHERE TO SUPPORT SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS FROM 24N TO 30N E OF 85W. THE DIURNAL SURFACE
TROUGH OVER THE SW GULF EXTENDS FROM 22N95W TO 18N95W MOVING W.
SCATTERED THUNDERSTORMS ARE WITHIN 50 NM OF THE TROUGH AXIS. A
1016 MB HIGH CENTERED NEAR 27N87W SUPPORTS MODERATE S TO SE
WINDS OVER THE WESTERN GULF WITH ANTICYCLONIC GENTLE TO MODERATE
WINDS OVER THE EASTERN GULF. CONVECTION WILL CONTINUE THROUGH
TONIGHT OVER THE NORTHERN GULF ASSOCIATED WITH THE SHORTWAVE
ENERGY MOVING EAST. ADDITIONAL SHORTWAVE ENERGY WILL ENHANCE
CONVECTION ONCE AGAIN OVER THE NW GULF ON FRIDAY.

CARIBBEAN SEA...
UPPER LEVEL RIDGING IS CENTERED OVER THE W CARIBBEAN NEAR
18N86W. UPPER LEVEL TROUGHING EXTENDS FROM THE W ATLC TO PUERTO
RICO SW ACROSS THE CARIBBEAN TO NEAR 11N72W. THE UPPER RIDGE IS
PROVIDING A DIFFLUENT ENVIRONMENT THAT IS HELPING TO ENHANCE
CONVECTION ASSOCIATED WITH A WESTERN CARIBBEAN TROPICAL WAVE.
ANOTHER TROPICAL WAVE OS LOCATED OVER THE EASTERN CARIBBEAN.
PLEASE REFER TO THE TROPICAL WAVES SECTION FOR MORE DETAILS ON
THESE TWO WAVES. ASCENT ON THE EASTERN SIDE OF THE UPPER TROUGH
ALONG WITH MODERATE MOISTURE SUPPORTS ISOLATED MODERATE
CONVECTION OVER AND WITHIN 150 NM W OF THE LESSER ANTILLES S OF
14N. MODERATE TO FRESH TRADE WINDS ARE S OF 16N BETWEEN 71W AND
78W OVER THE CENTRAL CARIBBEAN. GENTLE TO MODERATE TRADE WINDS
ARE ELSEWHERE OVER THE CARIBBEAN. OVER THE NEXT 24 HOURS
CONVECTION WILL CONTINUE OVER THE SW CARIBBEAN. A TROPICAL WAVE
WITH THE REMNANTS OF GRACE WILL CROSS THE LEEWARD ISLANDS
TONIGHT WITH CONVECTION.

...HISPANIOLA...
SHALLOW MOISTURE OVER THE ISLAND WILL SUPPORT ISOLATED SHOWERS
AND THUNDERSTORMS THIS AFTERNOON AND EVENING. GENERALLY FAIR
WEATHER IS EXPECTED OVERNIGHT TONIGHT. A TROPICAL
WAVE...INCLUDING THE REMNANTS OF GRACE...WILL APPROACH THE
ISLAND FRIDAY NIGHT. THIS WILL LIKELY ENHANCE SHOWER AND
THUNDERSTORM ACTIVITY BEGINNING FRIDAY NIGHT...LASTING THROUGH
SATURDAY.

ATLANTIC OCEAN...
AN UPPER TROUGH IS OVER THE OHIO VALLEY WITH SHORTWAVE ENERGY
MOVING AROUND THE EASTERN PERIPHERY OF THE TROUGH ALONG THE
EASTERN US COAST. ONE SUCH SHORTWAVE SUPPORTS ISOLATED MODERATE
CONVECTION N OF 28N BETWEEN 76W AND 79W. A 1016 MB HIGH IS
CENTERED NEAR 28N74W AND IS LOCATED UNDERNEATH AN UPPER RIDGE
AXIS THAT EXTENDS FROM THE WESTERN CARIBBEAN. A SHARP TROUGH
ALONG 65W...DOWNSTREAM OF THE UPPER RIDGE AXIS...SUPPORTS
ISOLATED MODERATE CONVECTION FROM 22N TO 29N BETWEEN 63W AND
71W. T.D. EIGHT IS JUST NORTH OF OUR AREA OF DISCUSSION WITH
CONVECTION EXTENDING AS FAR S AS 28N. PLEASE REFER TO THE
SPECIAL FEATURES SECTION FOR MORE DETAILS. RIDGING OVER THE
CENTRAL AND EASTERN ATLC IS SUPPORTED BY A PAIR OF HIGH CENTERS
WITH A 1019 MB HIGH NEAR 25N41W AND A 1020 MB HIGH NEAR 29N26W.
JUST NE OF THIS RIDGING IS A 1016 MB LOW NEAR 19N35W WITH A
SURFACE TROUGH THAT EXTENDS W TO 29N48W. ISOLATED MODERATE
CONVECTION IS WITHIN 175 NM N AND E OF THE LOW CENTER. THREE
TROPICAL WAVES ARE OVER THE TROPICAL ATLC. PLEASE REFER TO THE
TROPICAL WAVES SECTION FOR MORE DETAILS. OVER THE NEXT 24 HOURS
CONVECTION WILL PERSIST WITHIN SEVERAL HUNDRED MILES OF THE E US
COAST ASSOCIATED WITH THE TROUGH OVER THE US.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
LATTO
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